Use shader based blending to clamp kPlus mode w/F16

Bug: skia:6173
Change-Id: I21042d484d9a7b3eee04aa3301d9793d00ad6908
Reviewed-on: https://skia-review.googlesource.com/48183
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
diff --git a/gm/convexpolyeffect.cpp b/gm/convexpolyeffect.cpp
index a4fb5e5..16a185c 100644
--- a/gm/convexpolyeffect.cpp
+++ b/gm/convexpolyeffect.cpp
@@ -54,9 +54,10 @@
 
     FixedFunctionFlags fixedFunctionFlags() const override { return FixedFunctionFlags::kNone; }
 
-    RequiresDstTexture finalize(const GrCaps& caps, const GrAppliedClip* clip) override {
-        auto analysis = fProcessors.finalize(
-                fColor, GrProcessorAnalysisCoverage::kNone, clip, false, caps, &fColor);
+    RequiresDstTexture finalize(const GrCaps& caps, const GrAppliedClip* clip,
+                                GrPixelConfigIsClamped dstIsClamped) override {
+        auto analysis = fProcessors.finalize(fColor, GrProcessorAnalysisCoverage::kNone, clip,
+                                             false, caps, dstIsClamped, &fColor);
         return analysis.requiresDstTexture() ? RequiresDstTexture::kYes : RequiresDstTexture::kNo;
     }